Hello Seema,
I suggest you send someone to the post office and find out who is the post man assigned to your area. Get their mobile number, call him and tell them you are expecting an important letter.
We always give some tip money to our postman whenever he brings us a letter, that way he knows that If he delivers, he will get a tip. He even has my husband's mobile number and he always calls when anything for my husband arrives. He usually gives him 100 - 200 rupees for any parcel he brings.
Come on, we live in Pakistan and this is the system here, nothing to be ashamed about. Bribe (Tip) the postman!!
Cheers,
Tania